Definition 2.11: The mapping class group is
\(\operatorname{\sf Diff}(M)/\operatorname{\sf Diff}_0(M)\) . It
naturally acts on \(\operatorname{\sf Teich}\) . The quotient of \(\operatorname{\sf Teich}\)  by this action
may be viewed as the “moduli space” for \(M\) . However, this space is too
non-Hausdorff to be useful: any two open subsets of \(\operatorname{\sf Teich}/\operatorname{\sf Diff}\) 
intersect ([1]}, [2]}).
